Membrane with surface structure

ABSTRACT

A waterproof membrane, a method for sealing substructures, and a system for reflecting sunlight are disclosed. The waterproof member can include a barrier layer, which contains a thermoplastic material, and wherein an upper face of the barrier layer has an arithmetic mean roughness value R a  in accordance with DIN EN ISO 4287: 1998-10 of about 0.01-0.8 μm.

RELATED APPLICATION(S)

This application claims priority as a continuation application under 35 U.S.C. §120 to PCT/EP2012/072625, which was filed as an International Application on Nov. 14, 2012, designating the U.S., and claiming priority to European Application No. 11189212.1 filed in Europe on Nov. 15, 2011. The entire contents of these applications are hereby incorporated herein by reference in their entireties.

FIELD

The disclosure relates to a membrane, for example, a waterproof membrane, and methods for sealing substructures and increasing the energy output of bifacial or multifacial photovoltaic elements.

BACKGROUND INFORMATION

It is known, for example, for (flat) roofs, to use membranes that can reflect sunlight in order to help prevent buildings from becoming overheated. As a result of the reflectivity of these roofing materials, the absorption of solar radiation and the conversion thereof to heat can be reduced. In recent years, photovoltaic systems, so-called bifacial or multifacial photovoltaic elements, have become available, in which an active cell can also be located on the reverse side, which can allow the electromagnetic radiation that is reflected from the roof to also be converted to electrical energy.

It is known that (flat) roofs can become soiled over their service life. This soiling can occur as the roof is being laid, for example, or can be caused over the service life of the roof by particles such as soot, humus, sand and leaves.

Such soiling not only results in unsightly surfaces, for example, in the case of white or colored surfaces, but can also diminish the reflective capacity of these roofing materials.

SUMMARY

A waterproof membrane is disclosed comprising: a barrier layer, wherein the barrier layer includes a thermoplastic material; and wherein an upper face of the barrier layer has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of about 0.01-0.8 μm.

A method for sealing substructures is disclosed, the method comprising: applying a waterproof membrane to a substructure, the waterproof membrane having a barrier layer, wherein the barrier layer includes a thermoplastic material, and wherein an upper face of the barrier layer has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of about 0.01-0.8 μm; and directing the upper face of the waterproof membrane away from the substructure.

A system for reflecting sunlight is disclosed, the system comprising: a structure; and a waterproof membrane applied to the structure, the waterproof membrane having a barrier layer, wherein the barrier layer includes a thermoplastic material; and wherein an upper face of the barrier layer has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of about 0.01-0.8 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will now be further explained by way of an exemplary embodiment and with reference to the accompanying drawings, in which:

FIG. 1 shows a cross-section of an exemplary membrane according to the disclosure;

FIG. 2 shows a cross-section of an exemplary membrane according to the disclosure;

FIG. 3 shows a cross-section of an exemplary membrane according to the disclosure;

FIG. 4 shows a bifacial or multifacial photovoltaic element situated on an exemplary membrane according to the disclosure;

FIG. 5 shows measurements of unrolling forces after storage at various temperatures; and

FIG. 6 shows measurements of reflection in a soiling experiment according to an exemplary embodiment.

DETAILED DESCRIPTION

The disclosure relates to a waterproof membrane having a barrier layer, with the barrier layer including a thermoplastic material. In accordance with an exemplary embodiment, the barrier layer can have an arithmetic mean roughness value R_(a) of 0.01-0.8 μm in accordance with DIN EN ISO 4287: 1998-10.

In accordance with an exemplary embodiment, membranes of this type offer can have a diminished susceptibility to soiling and are easier to clean. Moreover, the force to unroll such membranes when they are in the rolled-up state can also be reduced, for example, after the membranes have been stored at temperatures above 60° C.

In accordance with an exemplary embodiment, the present disclosure relates to a waterproof membrane 1, which can include a barrier layer 2, wherein the barrier layer contains a thermoplastic material, for example, thermoplastic polyolefins or polyvinyl chloride (PVC), for example, polypropylene (PP) or polyethylene (PE). The upper face 3 of the barrier layer 2 can have an arithmetic mean roughness value R_(a) of 0.01-0.8 μm, for example, 0.025-0.5 μm, for example, 0.05-0.2 μm, in accordance with DIN EN ISO 4287: 1998-10.

FIG. 1 shows an exemplary membrane 1 in accordance with the disclosure. In accordance with an exemplary embodiment, the term “membrane” can include flexible, flat plastics having a thickness of 0.1 to 5 mm, for example, of 0.5 to 4 mm, which can be rolled up. In addition to films, which can have a thickness of less than 1 mm, membranes can also include sealing webs, such as are used for sealing roofs or terraces, for example, in thicknesses of 1 to 3 mm, and in some cases having a thicknesses of as much as 5 mm. In accordance with an exemplary embodiment, membranes of this type can be produced by coating, pouring, calendering or extrusion, and can be commercially available in the form of rolls, or are produced on site. The membranes can be single-layered or multilayered in structure. In addition, the membranes as disclosed herein, can also contain other accessory agents and processing agents, such as filler materials, UV stabilizers and heat stabilizers, softeners, release agents, biocides, fire retardants and antioxidants. For example, in accordance with an exemplary embodiment, membrane 1 according to the disclosure can be a roofing membrane.

The membrane can have a thickness of 0.1 to 5 mm, for example, 0.5 to 4 mm, and for example, 1 to 3 mm.

The upper face 3 of the barrier layer 2 can have an arithmetic mean roughness value (arithmetic mean of profile ordinates) R_(a) of 0.01-0.8 μm, for example, 0.025-0.5 μm, in accordance with DIN EN ISO 4287: 1998-10. In accordance with an exemplary embodiment, the arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 can be 0.05-0.2 μm.

An arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of 0.01-0.8 μm can decrease susceptibility to soiling. In addition, such surfaces can be easier to clean.

The force that is used to unroll such membranes when they are in the rolled-up state can be decreased in relation to membranes that have an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of more than 0.8 μm, for example, of more than 3 μm, for example, after such membranes have been stored at temperatures above 60° C.

In accordance with an exemplary embodiment, the total surface area of the upper face 3 has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of for example, ≧50%, for example, ≧80%, and for example, ≧98%.

The upper face 3 of the barrier layer 2 can have an embossed pattern 4, which can result in the abovementioned arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10.

The embossed pattern 4 can be a uniform embossed pattern.

In accordance with an exemplary embodiment, the color of the upper face 3 of the barrier layer 2 can be such that the relevant proportions of cyan, magenta, yellow and black on the upper face 3 of the barrier layer 2 do not exceed 5% in the CMYK color model. For example, the color can be white. In accordance with an exemplary embodiment, for example, the entire upper face 3 can be white.

For example, if the upper face is bright, for example, in the case of a color for which the respective percentages of cyan, magenta, yellow and black do not exceed 5% in the CMYK color model, a low susceptibility to soiling can be obtained because the soiling of bright surfaces can be perceived as objectionable and/or the reflective capacity of electromagnetic radiation, for example, of sunlight, can be reduced.

The barrier layer 2 can contain pigments 5, with the proportion of the pigments being 1-40 wt/%, for example, 10-30 wt/%, referred to the total weight of the barrier layer.

The pigments 5 can have an SRI (Solar Reflectance Index according to ASTM E 1980) of ≧70, for example, ≧78.

The pigments 5 can be selected from the group including of barium sulfate, zinc oxide, magnesium oxide, zirconium oxide and titanium oxide, for example, titanium oxide.

In accordance with an exemplary embodiment, the presence of pigments 5 in the barrier layer 2 can cause electromagnetic solar radiation to be reflected by the membrane 1, which can increase the energy output of bifacial or multifacial photovoltaic elements, for example, and/or decreasing the amount of thermal energy that is absorbed by buildings. The presences of pigments can also decreasing the susceptibility to soiling.

The waterproof membrane 1 can include a barrier layer 2. The barrier layer 2 can be made of materials that can provide water tightness at high fluid pressures.

In accordance with an exemplary embodiment, the barrier layer 2 can be highly resistant to water pressure and weather, and can achieve high scores in tear propagation tests and perforation tests, which can be desirable with respect to mechanical loads that are exerted on building sites. A resistance to sustained mechanical loads, for example wind, can also be desirable. The material of the barrier layer can be a flexible material.

The barrier layer can contain a thermoplastic material, for example, thermoplastic polyolefins or polyvinyl chloride (PVC), for example, polypropylene (PP) or polyethylene (PE), which can result in a high resistance to environmental factors.

The barrier layer 2 can be selected from materials from the group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), polyethylene (PE), polyvinyl chloride (PVC), ethylene/vinyl acetate copolymer (EVA), chlorosulfonated polyethylene, olefin-based thermoplastic elastomers (TPE-O, TPO) and polyisobutylene (PIB), and mixtures thereof.

The barrier layer 2 can consist of 50 to 100 wt/%, for example, 80 to 90 wt/%, one of the abovementioned materials, referred to the total weight of the barrier layer.

The barrier layer 2 can have a thickness of 0.1-5 mm, for example, 0.5-2.5 mm, for example, 1-2 mm.

In accordance with an exemplary embodiment, the thickness of membrane 1 can comprise 20% to 100% of the thickness of the barrier layer 2.

The membrane 1 can contain a fibrous material 6, for example, a woven fabric, a non-crimp fabric or a non-woven fabric. The fibrous material can be attached to the barrier layer, as shown in FIG. 2, for example, or can be integrated into the barrier layer, as shown in FIG. 3. In accordance with an exemplary embodiment, a fibrous material 6, for example, a woven fabric, a non-crimp fabric or a non-woven fabric, can be incorporated into the barrier layer 2.

In accordance with an exemplary embodiment, the fibrous material 6 can be a material that is composed of fibers. The fibers can include or consist of organic, inorganic or synthetic material. For example, the fibers can be cellulose fibers, cotton fibers, protein fibers, glass fibers or synthetic fibers. Synthetic fibers can be fibers made of polyester or of a homopolymer or copolymer of ethylene and/or propylene or of viscose. These fibers can be short fibers or long fibers, spun, woven or non-woven fibers or filaments. Furthermore, the fibers can be directed or stretched fibers.

In accordance with an exemplary embodiment, the body constructed from the fibers can be produced using a very wide range of methods known to a person skilled in the art. For example, the bodies that include a woven fabric, a non-crimp fabric or a knitted fabric can be used.

In accordance with an exemplary embodiment, a fibrous material can be a woven fabric, a non-crimp fabric or a non-woven fabric. In accordance with an exemplary embodiment, the fibrous materials can have a mesh count (or mesh number), for example, of 5-40 per 10 cm.

In accordance with an exemplary embodiment, the fibrous material 6 can be capable of protecting the barrier layer 2 against mechanical loads. For example, during the installation and mounting of waterproof membrane 1, heavy mechanical loads can occur, for example, from installers walking on the waterproof membrane. In accordance with an exemplary embodiment, the fibrous material 6 can have a certain base weight, and therefore a certain pressure resistance to mechanical loads. For example, suitable are fibrous materials, for example, woven fabrics, non-crimp fabrics or non-woven fabrics, which can have a base weight of 30-200, for example, of 50-150 g/m².

In accordance with an exemplary embodiment, the fibrous material 6 can consist of a thermoplastic material, and the material can be selected from the group including high-density polyethylene (HDPE), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), polyvinyl chloride (PVC), polyamide (PA) and combinations thereof.

In accordance with an exemplary embodiment, the fibrous material 6 can consist of an inorganic material, for example, glass.

In accordance with an exemplary embodiment, the disclosure relates to the use of a waterproof membrane 1 as disclosed herein for increasing the amount of sunlight that can be reflected off of buildings, for example, roofs of buildings.

In accordance with an exemplary embodiment, the disclosure relates to the use of a waterproof membrane 1 as disclosed herein for increasing the energy output of bifacial or multifacial photovoltaic elements 8.

The energy output of bifacial or multifacial photovoltaic elements 8 can be increased by using the membrane according to the disclosure, as a result of which the percentage of electromagnetic radiation coming from the membrane and striking the photovoltaic element, referred to the total amount of electromagnetic radiation that strikes the membrane, can be higher than with membranes of the known art. The source of the electromagnetic radiation that strikes the membrane can be the sun. The electromagnetic radiation coming from the membrane according to the disclosure can include reflected electromagnetic radiation.

In accordance with an exemplary embodiment, the disclosure relates to a structure, for example, a building structure, for example, a building or a sports arena, including a waterproof membrane 1 as described above. For example, the membrane 1 can be mounted on the roof of the structure. In accordance with an exemplary embodiment, bifacial or multifacial photovoltaic elements 8 can be located on the membrane.

In an accordance with an exemplary embodiment, the disclosure relates to a method for sealing substructures 7, including the following steps: i) applying a waterproof membrane, such as the membrane disclosed herein, to a substructure 7, with the upper face 3 of the waterproof membrane 1 being directed away from the substructure 7.

The method can also include the step of: ii) of mounting at least one bifacial or multifacial photovoltaic element 8 on the upper face 3 of the waterproof membrane 1.

The membrane can be arranged at a distance of 20-200 cm from at least one bifacial or multifacial photovoltaic element 8 on a substructure 7, on which the at least one bifacial or multifacial photovoltaic element can also be mounted.

The substructure 7 can be a structure such as a building or a sports arena. The substructure 7 can be, for example, a part, for example, the roof, of a structure, for example, a building.

The membrane 1 can be produced by any method. For example, the membranes can be produced using commercial machinery. The membranes can be produced in a single process step as a continuous product, for example, by extrusion and/or calendering and/or laminating and/or bonding, and can be rolled up onto reels, for example. The stock temperature in the extruder or the calender can range from 120° C.-250° C., for example 130° C.-220° C., for example 180° C.-220° C., for example, during extrusion and/or calendering and/or laminating and/or bonding.

In accordance with an exemplary embodiment, to help ensure that the upper face of the barrier layer will have an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of 0.01-0.8 μm, for example, of 0.025-0.5 μm, an embossing roller can be used, for example.

In an accordance with an exemplary embodiment, the disclosure relates to the use of an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of 0.01-0.8 μm, for example, of 0.025-0.5 μm, on the upper face 3 of a barrier layer 2 of a waterproof membrane 1, wherein the barrier layer contains a thermoplastic material, for example, thermoplastic polyolefins or polyvinyl chloride (PVC), for the purpose of reducing the force to unroll the waterproof membrane 1 after heated storage, at storage temperatures above 60° C., for example, ≧70° C.

In accordance with an exemplary embodiment, the barrier layer and the waterproof membrane as disclosed herein can have the arithmetic mean roughness value R_(a), for example, involves an embossed pattern 4, for example, a uniform embossed pattern. For example, ≧50%, for example ≧80%, for example, ≧98% of the total area of the upper face 3 can have an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 as described above.

The level of unrolling force (take-off tension) can be measured using a tension gauge, in which rolls of the waterproof membranes can be unrolled by means of a take-off device via the tension gauge, and the level of take-off tension can be determined. Heated storage, at storage temperatures above 60° C., for example, ≧70° C., for example at 70° C. or 80° C., can be carried out in a cabinet dryer for a period of 24 hours, followed by storage at 23° C. for a period of 24 hours.

In accordance with an exemplary embodiment, the membrane 1 according to the disclosure can be embodied as a sealing membrane web, which can consist of a barrier layer 2 made of thermoplastic polyolefins. For example, the thickness of the barrier layer can be about 2 mm. The upper face of the barrier layer has can have an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of, for example, 0.1 μm.

In accordance with an exemplary embodiment, the susceptibility to soiling and the force to unwind a roll of a membrane (E) according to the disclosure, with a barrier layer upper face that has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of 0.1 μm, has been compared with the susceptibility to soiling and the force to unwind a roll of a membrane (V) not according to the disclosure, with a barrier layer upper face that has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of 3 μm. Both membranes had a thickness of 2 mm, and the barrier layers were made of thermoplastic olefins.

The reflectance properties of the two membranes E and V were measured (before experiment) using a Solyndra Albedometer Model H 500, after which the two membranes E and V were walked upon with street shoes for a period of 45 days, and the reflectance properties were measured once again (uncleaned after experiment). Afterward, the two membranes E and V were cleaned using simple cleansing materials (wet sponge with a small amount of commercial cleaning agent), and the reflectance properties were measured again (cleaned after experiment). As is shown in FIG. 6, the membrane (E) according to the disclosure having a barrier layer that has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of 0.1 μm is less heavily soiled and can be cleaned more easily than the membrane (V) not according to the disclosure, which has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of 3 μm.

Rolls of the two membranes E and V, measuring 15 m in length and 25 cm in width, were stored in a cabinet drier at 60° C., 70° C. or 80° C. for a period of 24 hours, after which the two membranes were stored at 23° C. for a period of 24 hours. These rolls were then unrolled by means of a take-off device equipped with a tension gauge, and the level of force for unrolling (take-off tension) was measured. The rolls were stored in the cabinet drier at different temperatures in order to ascertain the behavior of the membranes under different storage/transport conditions. As is shown in FIG. 5, the membranes E according to the disclosure unexpectedly exhibit substantially lower levels of unrolling force, for example, when stored at temperatures above 60° C.

Thus, it will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.

LIST OF REFERENCE SIGNS

-   1 Waterproof membrane -   2 Barrier layer -   3 Upper face of the barrier layer -   4 Embossed pattern -   5 Pigments -   6 Fibrous material -   7 Substructure -   8 Bifacial or multifacial photovoltaic element 

What is claimed is:
 1. A waterproof membrane comprising: a barrier layer, wherein the barrier layer includes a thermoplastic material; and wherein an upper face of the barrier layer has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of about 0.01-0.8 μm.
 2. The waterproof membrane according to claim 1, wherein the thermoplastic material is thermoplastic polyolefins or polyvinyl chloride (PVC).
 3. The waterproof membrane according to claim 1, wherein the barrier layer has the arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of the barrier layer of about 0.025-0.5 μm.
 4. The waterproof membrane according to claim 1, wherein the upper face of the barrier layer comprises: an embossed pattern.
 5. The waterproof membrane according to claim 1, wherein a color of the upper face of the barrier layer is such that proportions of cyan, magenta, yellow and black on the upper face of the barrier do not exceed about 5% in a CMYK color model.
 6. The waterproof membrane according to claim 1, comprising: pigments in the barrier layer, and wherein a ratio of the pigments to a total weight of the barrier layer is about 1-40 wt/%.
 7. The waterproof membrane according to claim 6, wherein the ratio of the pigments to the total weight of the barrier layer is about 10-30 wt/%.
 8. The waterproof membrane according to claim 6, wherein the pigments are selected from the group consisting of: barium sulfate, zinc oxide, magnesium oxide, zirconium oxide and titanium oxide,
 9. The waterproof membrane according to claim 1, wherein a thickness of the membrane is about 20-100% of a thickness of the barrier layer.
 10. The waterproof membrane according to claim 9, wherein the thickness of the barrier layer is about 0.1-5 mm.
 11. The waterproof membrane according to claim 9, wherein the thickness of the membrane is about 0.1 to 5 mm.
 12. The waterproof membrane according to claim 1, wherein the membrane comprises: a fibrous material.
 13. The waterproof membrane according to claim 12, wherein the fibrous material comprises: a woven fabric, a non-crimp fabric, or a non-woven fabric.
 14. A method for sealing substructures, the method comprising: applying a waterproof membrane to a substructure, the waterproof membrane having a barrier layer, wherein the barrier layer includes a thermoplastic material, and wherein an upper face of the barrier layer has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of about 0.01-0.8 μm; and directing the upper face of the waterproof membrane away from the substructure.
 15. The method according to claim 14, wherein the substructure is a roof of a building.
 16. A system for reflecting sunlight, the system comprising: a structure; and a waterproof membrane applied to the structure, the waterproof membrane having a barrier layer, wherein the barrier layer includes a thermoplastic material; and wherein an upper face of the barrier layer has an arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of about 0.01-0.8 μm.
 17. The system according to claim 16, wherein the upper face of the waterproof membrane is directed away from the structure.
 18. The system according to claim 16, wherein the thermoplastic material is thermoplastic polyolefins or polyvinyl chloride (PVC).
 19. The system according to claim 16, wherein the barrier layer has the arithmetic mean roughness value R_(a) in accordance with DIN EN ISO 4287: 1998-10 of the barrier layer is about 0.025-0.5 μm.
 20. The system according to claim 16, wherein the upper face of the barrier layer comprises: an embossed pattern. 